RxJs and window's postMessage for intercommunication

host.js

import * as Rx from "rxjs/Rx";
import * as uuid from "uuid";
import {IRequest} from "./common";

let button = document.querySelector("button");

let iframe = document.createElement("iframe");
iframe.src = "/proxy.html";
document.body.appendChild(iframe);

button.onclick = function() {
    request("https://request.url");
};


function request(url: string) {
    const requestId = uuid.v4();
    const req: IRequest = {
        id: requestId,
        payload: {
            url
        }
    };

    iframe.contentWindow.postMessage(req, "*");
    return Rx.Observable.fromEvent(window, "message")
            .filter((messageEvent: MessageEvent) => messageEvent.data && messageEvent.data.id === requestId)
            .map((messageEvent: MessageEvent) => messageEvent.data));
}

proxy.js

import * as Rx from "rxjs/Rx";
import {IResponse} from "./common";
const messages = Rx.Observable.fromEvent(window, "message")
                    .filter((messageEvent: MessageEvent) => messageEvent.data && !!messageEvent.data.id);

messages.subscribe((event: MessageEvent) => {
    const response: IResponse = {
        id: event.data.id,
        payload: event.data.payload
    };

    event.source.postMessage(response, event.origin);
});